Can't download image for profile and blavatar

I've been trying to download a picture to my profile, as well as the ' blavatar', but thus far it's not showing - plus, in the blavatar dowload the tools for editing/cutting the picture down't show on my screen.
do some applications work better on PC versus Mac, perhaps ?

Any answer to help me solve the problem is greatly appreciated,
Thanks,
sincerely,

I've tried uploading a blavatar at all sizes for the last few days. Each time it lets me crop it, and once I've cropped it and clicked 'save', it's as if nothing's happened and the blog still has no picture. Any advice...?